Phytoplankton in Zhejiang coastal waters were studied to understand their distribution and relationship with the environment. The researchers found 326 species of phytoplankton, with Diatoms and Pyrrophyta being the most common. The abundance of phytoplankton varied between spring and neap tides, with higher amounts during spring tide in some areas. Noctiluca scintillans was more abundant in the north and inside sea area. The dominant species were Skeletonema costatum, Leptocylindrus danicus, and others. The phytoplankton community was divided into five ecological groups, with neritic eurytropic species being the main ones. Overall, the phytoplankton community structure was better during spring tide in the inside sea area, while it was more stable in the outside sea area.